DESCRIPTION: The Subcommittee scored in full time and amount this competing renewal Senior Research Scientist Development Award (K05) application to continue the Candidate's long-standing research program regarding the molecular mechanism of opioid drugs and to determine the molecular and gene structure of opioid receptors in immune cells and periaqueductal gray (PAG) with special attention to understanding tissue specific regulation of opioid receptor gene expression and the molecular basis of opioid tolerance/dependence.Scoring was recommended because the Candidate has an excellent record over the past 20 years in helping to characterize the opioid receptor system. This commitment to opiate research over the years has provided enormous impetus to the field. He has trained numerous investigators who have gone on to establish excellent laboratories of their own. This work is state of the art and far-sighted; this award will provide him with the means to continue his endeavor. No human subjects are involved. Vertebrate animals (rats, mice, rabbits) will be used in accordance with accepted humane standards and their care was judged to be adequate.